Trainers can be good or bad. But here’s a rough idea what I do which should be a good starting point.
All Exercises 3 sets of 8-12 reps. Last rep should be close to failure or else you’re not pushing yourself hard enough. When you pick your exercises for each muscle group you want to pick ones that will hit different parts of that muscle. Somtimes I take the last set of each exercise to failure and add in a dropset, but that’s just me.
Day 1: Back/Biceps
3-4 back exercises 1-3 bicep exercise
Day 2: Chest/Triceps
3-4 chest exercises 1-3 tricep exercises
Day 3: Legs
Day 4: Shoulders/Traps
3 shoulder exercises 1-2 trap exercises